Types of Foundation Cracks and What They Mean for Your Atlanta Home

Finding a crack in your foundation is unsettling. But before you panic (or ignore it), you need to understand what the crack is telling you. Some foundation cracks are completely normal. Others indicate serious structural problems that will only get worse. Here's how to tell the difference.

Vertical Cracks

Vertical cracks run straight up and down (or nearly so—within 30 degrees of vertical). These are the most common type of foundation crack and are usually the least concerning. They're typically caused by concrete curing and natural settling during the first few years after construction. In most cases, vertical cracks under 1/8 inch wide are cosmetic and can be sealed to prevent water entry. However, vertical cracks that are wider than 1/4 inch, growing over time, or showing displacement (one side higher than the other) may indicate more significant settling that needs professional evaluation.

Horizontal Cracks

Horizontal cracks are the most serious type of foundation crack. They run sideways across your basement or foundation wall and indicate lateral pressure—typically from water-saturated soil pushing against the wall from outside. In Atlanta, this is directly related to our clay soil. When Georgia's red clay absorbs water, it expands with enormous force against foundation walls. Over time, this hydrostatic pressure can cause the wall to bow inward, and horizontal cracks are the warning sign. If you see a horizontal crack, especially one in the middle third of the wall, contact a foundation professional immediately.

Stair-Step Cracks

Stair-step cracks follow the mortar joints in block or brick foundations, creating a pattern that looks like a staircase. These indicate differential settling—one part of your foundation is sinking more than another. Stair-step cracks are common in Atlanta homes built on slopes or where soil conditions vary under different parts of the foundation. Minor stair-step cracking (hairline, stable) may just need monitoring. But if the cracks are wider than 1/4 inch, actively growing, or accompanied by wall displacement, foundation repair is needed.

Diagonal Cracks

Diagonal cracks run at roughly a 45-degree angle and typically indicate differential settlement—similar to stair-step cracks but in poured concrete foundations. They often originate from the corners of windows or doors and extend outward. Diagonal cracks wider than 1/4 inch, or those where one side has shifted relative to the other, usually mean the foundation is actively moving and needs stabilization.

Hairline Cracks vs. Structural Cracks

Width matters. Hairline cracks (less than 1/16 inch) are almost always cosmetic—they result from concrete shrinkage during curing and rarely worsen. Cracks between 1/16 and 1/4 inch should be monitored. Mark them with tape, date them, and check back in 3-6 months. If they're growing, get a professional assessment. Cracks wider than 1/4 inch, or any crack showing displacement, are structural concerns that warrant immediate professional evaluation.

When Cracks Also Mean Water Problems

Foundation cracks aren't just structural concerns—they're also entry points for water. Even hairline cracks can allow water to seep into your basement during heavy Atlanta rainstorms. If you notice water stains, dampness, or efflorescence (white mineral deposits) around any crack, you have both a structural and a waterproofing issue to address.

How Foundation Cracks Are Repaired

Repair methods vary based on the crack type and severity. Cosmetic cracks can be sealed with epoxy or polyurethane injection to prevent water entry. Structural cracks from settling typically require foundation underpinning—push piers or helical piers are driven to stable soil or bedrock to permanently support the foundation. Wall cracks from lateral pressure may require wall anchors, carbon fiber reinforcement, or in severe cases, wall reconstruction. The right repair depends on an accurate diagnosis of why the crack occurred.

Get a Professional Assessment

If you're unsure about a crack in your foundation, get it looked at. Early intervention is almost always less expensive than waiting. At Reliable Solutions Atlanta, we provide free foundation inspections. We'll identify the type and cause of your cracks, explain whether they're cosmetic or structural, and recommend the most appropriate repair if one is needed. Call 770-895-2039 to schedule yours.